Gadgetbridge - A free and cloudless replacement for your gadget vendors' closed source Android applications.
fitbit - The Fitbit mobile app is for people who use Fitbit fitness trackers to keep track of their activity goals, food plans, and other fitness related things. Read more about fitbit.
Strava - The #1 app for runners and cyclists
Amazfish - SailfishOS companion application for Huami Devices (such as Amazfit Bip, Cor, Mi Band 2/3 and GTS), PineTime InfiniTime and Bangle.js
Polar Loop 2 - Polar Loop 2 is a digital activity tracker for those who wants to track their activity 24/7 and are interested in to reach activity goals via smart guidance.
Treekly - Turn footsteps into forests.